1. Technical Field
The present invention generally relates to the field of clinical chemistry. More particularly, the present invention relates to a diagnostic imaging system that analyzes the color change associated with one or more test areas on sample media following contact thereof with a liquid specimen, such as urine or blood.
2. Background Information
Throughout this application, various patents are referred to by an identifying citation. The disclosures of the patents referenced in this application are hereby incorporated by reference into the present disclosure.
Reagent test strips are widely used in the field of clinical chemistry. A test strip usually has one or more test areas, and each test area is capable of undergoing a color change in response to contact with a liquid specimen. The liquid specimen usually contains one or more constituents or properties of interest. The presence and concentrations of these constituents or properties are determinable by an analysis of the color changes undergone by the test strip. Usually, this analysis involves a color comparison between the test area or test pad and a color standard or scale. In this way, reagent test strips assist physicians in diagnosing the existence of diseases and other health problems.
Color comparisons made with the naked eye can lead to imprecise measurement. Today, strip reading instruments exist that employ reflectance photometry for reading test strip color changes. These instruments accurately determine the color change of a test strip within a particular wavelength range or bandwidth. Some instruments may also measure color inconsistencies outside this bandwidth. For example, instruments such as those sold under the CLINITEK® trademark by Bayer Healthcare Diagnostics Division of Bayer HealthCare LLC (Medfield, Massachusetts) and/or as disclosed in U.S. Pat. No. 5,408,535, may detect features such as traces of blood within a urine specimen on a MULTISTIX® (Bayer) reagent strip. After the urine specimen contacts the test pad of a MULTISTIX® reagent strip, intact blood cells appear as small green blotches on the yellow test area. These existing strip readers can detect both the overall color of the test pad and the small blotches of green.
U.S. Pat. No. 5,055,261 discloses a multiple-strip reading instrument utilizing reflectance photometry to read test strips. An operator sequentially places the test strips transversely in a loading area. An arm orients the test strips on rails extending from the loading area to one or more reading stations employing read heads.
This instrument includes an indexing mechanism that incrementally advances the strips in spaced parallel relation a predetermined distance along the rails. After each incremental advance, each test strip dwells for a predetermined time period in its new position. Consequently, individual test strips sequentially advance to a reading position where, during the dwell period, certain test areas are read. Subsequently, the instrument advances the test strip to the next reading position where the instrument reads the other test areas on the test strip with longer incubation times.
An instrument embodied in U.S. Pat. No. 5,143,694 also transports test strips from a strip loading area, along a transport path under the read heads, and then to a waste receptacle.
A common feature of these instruments is that their relative size and complexity, particularly with respect to those utilizing automated test pad transport systems, render them relatively unportable. Rather, these devices tend to be installed at a dedicated testing center or laboratory, where samples are aggregated and tested in bulk. Unfortunately, such aggregation of samples from multiple patients presents opportunities for error due to mislabeling of the samples and/or the test results. Moreover, in many instances, the time required for transporting the samples to and from the processing center, and for testing and recording the results, may be problematic.
A need therefore exists for an improved diagnostic testing device that enables a care provider to obtain quick and accurate test results without the need for sending sample media to a remote testing center for processing.